The La Toscana Village is a shopping mall like most others in Tucson, except it happens to be in one of the city's tonier neighborhoods. Here, the rugged Santa Catalina Mountains give way to gently rolling foothills in the high desert. Many of Tucson's prominent families live in the area, in sprawling ranch-style homes, surrounded by well-groomed flora. The mall has banks, a flower shop and, at the back of the parking lot of the Safeway, a Beyond Bread, the favorite bakery belonging to Tucson's star restaurateur, Sam Fox. It was toward Beyond Bread, shortly after 10 a.m. on Saturday morning, that everyone ran when the shooting began at the La Toscana Safeway.

Just outside the supermarket, the local Congresswoman, Gabrielle Giffords, a Democrat who had just been sworn in for her third term in Washington, was a few minutes into of one of her regular town-hall-style meetings when a young man approached. He had reportedly been trying to speak to Giffords even before the event got underway but had been told to wait his turn. "He was intent," Alex Villec, a Giffords volunteer, told the Arizona Daily Star. "He was intent when he came back  a pretty stone-cold glance and glare." (Is violent rhetoric behind the attack on Giffords?)

The young man eventually got up close to the politician, took out a semi-automatic weapon with an extended clip and opened fire. He shot Giffords once in the head and sprayed the rest of the crowd with bullets, hitting a total of 19 people. Before he could do more damage or get away, he was tackled by two men in the crowd.

Emergency vehicles and medical helicopters soon converged, with the choppers landing in the eastbound lane of one of Tuscson's busiest intersections, which would be closed for close to seven hours.

So far, six of the victims have died, including nine-year old Christina Taylor Green, who was born on Sept. 11, 2001 and had just been elected to her school council, and a federal judge named John Roll, who, after attending Catholic church services in downtown Tucson, decided to drop by the Safeway to say hello to his friend, the congresswoman. "Unfortunately, he was in the wrong place at the wrong time," said Pima County Sheriff Clarence Dupnik, who provided some details at an evening press conference. Giffords remains in critical condition. But Dr. Richard Carmona, a former U.S. Surgeon General who now works with the Pima County Sheriff's Department  and who became an important local ally of Giffords during the heated debate over health care  said he had looked at her medical records at the hospital and that he had "guarded optimism" about her recovery. (See Giffords' congressional record.)

Meanwhile, by the time local officials held a press conference, media reports had identified the alleged shooter as Jared Lee Loughner, 22. Although the sheriff did not refer to the suspect by name, he mentioned various online postings that the media has attributed to Loughner. Dupnik also said that investigators believe the gunman had help from a white man in his mid-50s. The sheriff did not say how this second "person of interest" is believed to have played a role in the shooting.

[Update: On Sunday, the sheriff's department said that the "person of interest" was the cab driver who took the suspect to the supermarket. He had gone into the Safeway apparently because Loughner had to get change to pay the fare. He is no longer a person of interest, much less a suspect.]

Giffords was no stranger to danger or threats. Though she managed to eke out a victory in her most recent Congressional campaign, it had been rife with contention as anti-immigrant, anti-Obamacare rhetoric dominated the debate. Some windows of her congressional offices in Tucson were knocked out shortly after she cast her vote in favor of the President's health care reform. At the press conference on Saturday, Dupnik said police were investigating a suspicious package found at her offices. (See how Gifford and other Arizona Democrats grappled with immigration.)

Nevertheless, at her Safeway meet-and-greet, Giffords did not have any security forces with her. Dupnik said she was the shooter's main target, but declined to discuss details of the grocery's security camera footage. And although the sheriff did not speculate on the shooter's motive, Dupnik did say, "I have no reason to believe this individual was insane."

"Was he unstable?," Dupnik said at the press conference. "I would agree with that."

With the suspect in custody, the media has been parsing rambling online commentaries allegedly posted by Loughner. Among them: a video on YouTube ("I can't trust the current government because of fabrications. The government is implying mind control and brainwash on the people by controlling grammar") as well as what appeared to be a farewell message on Myspace ("Goodbye... Please don't be mad at me").

What is not clear is what role politics  and, in particular, the red-hot rhetoric of the mid-term elections  played in the shooting. Descriptions one of Loughner's high school classmates posted on Twitter only added to the mystery. "He had a lot of friends until he got alcohol poisoning in '06, & dropped out of school. Mainly loner very philosophical," @caitieparker tweeted. "As I knew him he was left wing, quite liberal. & oddly obsessed with the 2012 prophecy." And, most ominously, "He was a political radical & met Giffords once before in '07, asked her a question & he told me she was 'stupid & unintelligent.'"

Loughner lived with his family in a small, 1,400 sq. ft. house in a part of Tucson quite different from the well-to-do La Toscana. The buildings need renovating, the landscaping is overgrown. Like many of the homes in this blue-collar, multi-racial neighborhood, the Loughners' property has a sign that discourages solicitors. By Saturday evening, the police had set up a perimeter around the house and the immediate homes nearby. (See TIME's complete coverage of the Tucson shooting.)

Neighbors say the Loughners kept to themselves, but weren't exactly unfriendly. The family, they say, had a passion for classic cars and were often seen driving up the street in 1970s-era muscle cars that they had worked on and restored. The father would occasionally exchange a neighborly wave. Still, Dawn Cook, 33, says she and her daughter avoided the house. "We go selling Girl Scout cookies door-to-door," says Cook, who works at her husband's Tucson scrapyard. "But we didn't go there," she says of the Loughners' house, because it appeared foreboding with its unkempt plants. (See TIME's most unforgettable images of 2010.)

"This has not become the nice United States of America that most of us grew up in," Dupnik said at his press conference, which took place at the posh Westward Look Resort, roughly half a mile from the crime scene. "And I think it's time that we do some soul-searching." He had opened the conference by blaming the media  particularly broadcast news and cable television's talking heads  for adding fuel to the "vitriol" that sets off these sorts of fires. He called it a "sad day for America."

U.S. Rep. Jeff Flake, an Arizona Republican who spoke at the press conference, said that Americans all "long for more civility everywhere, but I wouldn't want to ascribe what happened today to [political rhetoric]. Usually when we speak out on something like that, we are proven wrong." The Congressman said he disagreed with Giffords on a lot of issues, but that they were always friendly. Still, the risks of public life are changing the security equation for politicians. "I wouldn't want to reveal how security measures have changed," Flake said. "You never want that out there. But certainly, I'll be more careful."